The fake swede is on so many threads that it would make it very difficult to follow what was going on if I put him on ignore. But you carry on mate he loves the adulation.
The tee joint needs cutting out and renewing. The original soldered joint wasn't done properly. Has been leaking from the day it was originally plumbed in. Tiny pinprick gap in the solder. Trying to re-solder in situ I would not recommend as you won't be able to clean the joint properly. Drain...
My recently departed dad was a self employed plumbing and heating engineer. But he could turn his hand to most jobs in the building trade. He was a good man.Taught me all I know as I have for @Wrong-Direction.